All inner organs, central, peripheral and vegetative nervous system, vascular and lymphatic systems and muscular ligamentous apparatus are somehow or other concerned with human bony skeleton. From the position of biomechanics, the head, neck, trunk and extremities of a human are joined in statokinematic regions by the bone and muscular ligamentous structures. The most important skeleton formation is considered to be spinal column or backbone. The backbone performs protective, support and motor functions and is the main structure-forming organ. From the position of biomechanics, the backbone, pelvis and low extremities represent a whole statokinematic block.
Disorders in some part of this system lead to the disorders of functioning of other structures.
The spine column, functioning as a whole organ, represents a chain of connected vertebra-motor segments (VMS). VMS are joined by the two adjacent vertebras with the intervertebral disk, muscular ligamentous apparatus, lying between them. Movements in the area of VMS can be performed in normal, decreased and increased ranges, as well as in the zone of micro movements (“model” of joint). The backbone has the so-called physiological curvatures in sagittal plane—cervical and lumbar lordosis, thoracic and sacrococcygeal kyphosis. Curvatures in frontal plane are usually regarded as scoliosis or scoliosion, i.e. pathology, although many investigation works have proved that the minimal degree of curvature of the frontal plane is typical of all people and is normal. The combination of these disorders in the horizontal plane is regarded as asymmetric position of structures of the shoulder-girdle with respect to pelvis or as “torsion”.
The pelvis joins sacrum, adherent pair iliacs, ischial and pubic bones in a single block, having three joints: symphysis pubis, sacroiliac, right and left joints. Movements in these joints can be performed either within normal range or within limited or enlarged range (micro movements, “model” of joint).
The position of sacrum, which is located between the pelvis and spine column, determines the position of pelvis (inclination, lateral inclination, tortuosity) and spine column (the intensity of its curvature in all planes). It was determined that morphometric characteristics of backbone, pelvis bones and lower extremities had “spiral” in their basis and that human muscles were united into special muscular loops interacting according to the laws of spiral.
There are constitutionally determined types of constructive approaches to human support-motor apparatus. They are realized through morphological and functional asymmetries (“?” and “S”-shape spinal curvatures, types of “torsion” of spine column, relatively and absolutely short leg, “leading” leg, “jumping” leg, “support” leg, etc.).
While keeping the position of the body (statics) and moving the body (dynamics), the intensity of physiological curvatures and frontal deviations changes, as well as the position of inner organs, nervous, vascular and lymphatic system structures.
As a rule, functional asymmetries of support-motor apparatus and biomechanical characteristics of mobility of VMS are not considered in the sphere of human activity support (furniture, work tools, clothes, etc.). In a sitting posture supporting by gluteal regions, the determining factors involve the asymmetry of position of pelvis structures in all planes, the “switch-off” of the functions of iliopsoas and gluteus muscle, as well as other muscular groups, prelum abdominale and diaphragm muscles, specifically. The sitting device with additional support (chair back, etc.) consists in switching off the antigravity function of some muscles of the spinal column. Thus, in a sitting posture (statics), the protective and support structure-forming characteristics of the spinal column and all the biokinematic chain backbone-pelvis-lower extremities change and the load upon osteochondrous structures of the backbone, especially upon the lumbar VMS, increases.
The resulting influence of geophysical factors upon the human body, taking into consideration structural and functional asymmetries typical of the body, can be represented in the form of a long-pitch screw. Body constitution correspondingly counteracts the screwing effect, pressing the human body to the earth, in order to maintain the balance state. The form of spring and spiral mostly satisfies this condition.
Patent FR, A, 2589701 protects a device which provides optimal position of the body and neck in a sitting posture, comprising a supporting element of approximately rectangular form in frontal plane with front, supporting and back base layers, possessing different physical properties, provided with a case and fastening means.
Patent RU, 01, 2170539 protects an analogous device comprising a supporting element, consisting of two layers of symmetrical form or having the form of an airplane wing profile, with the depth of flexure from 0 to 50 cm in horizontal cross section, ratio of rigidity of layers—from 1:1.2 to 1:3. The back base layer has a vertical trough 2-8 cm wide and 0.5-3 cm deep.
These devices enable to ease down the lumbar muscle tension in a sitting posture, however are far from providing “optimal biomechanics of the body and neck”, which is declared by the applicants.
Patent RU, 01, 2063646 protects a sitting device, comprising a support, provided with a base in a top part thereof, on which a seat is mounted; the sitting device comprises also a backrest, headrest, armrest, foot loaders, underarm rests and seat belt. The operator can be working in a sitting position, can be resting in reclining and lying posture and performing physical exercises.
This engineering solution is taken as prototype of the present invention.
This engineering solution enables to ease down the fatigability in the sitting posture, however, as all other known engineering solutions, it does not consider the peculiarities of biomechanics of support-motor apparatus and other systems of human organism—mobility of osteochondrous ligamentous junctions in the region of micromotions (“model” of joint), constitutionally determined morphological and functional asymmetries of support-motor apparatus of a human; in a sitting posture resting upon buttocks, the main muscle forming a lumbar lordosis (iliopsoas muscle) is in a relaxed state, gluteus and prelum abdominale muscles are “switched off”; depending on the inclination angle of pelvis forward or aside, pelvis “tortuosity”, unequal distribution of support in the points of contact takes place, the load upon the spinal column, especially upon the lumbar part of the spine, sharply increases due to “switching off” of the lower extremities and pelvis from the biokinematic chain. It is worth mentioning thereby that the sitting posture is considered to have the biggest load for the spinal column, especially harmful is the kyphotic position of backbone, i.e. implying a slight forward inclination when the load upon the intervertebral disks, especially in the lumbar part of backbone, and upon postural muscles of spinal column increases, intra-abdominal pressure decreases because of enervation of prelum abdominale, people with low-grade fixing function of conjunctive tissue (hypermobile) experience descending of inner organs of abdominal cavity, disturbance of biomechanics of breathing, difficulty of bile outflow, etc.
“Congestive” effects in small pelvis take place, causing diseases or functional disorders of organs of small pelvis (haemorrhoid, prostatitis, impotence, frigidity, endometritis, etc., as well as dysfunction of lower parts of gastrointestinal tract, etc.); mechanical crossclamping of neurovascular trunks, coming to the lower extremities, occurs; due to the necessity to keep head in vertical position, overloads and spastic reactions occur in suboccipital group of muscles, causing impairment of blood circulation in vertebrobasilar system of vessels of the brain, feeding the brain stem and basal parts, i.e. parts comprising control centers of vital functions of the organism, although sitting with the two zones of support provided (seat and backrest), the overloads are not so pronounced, but a part of postural muscles “switches off”, which leads to a non-even increase of loads upon the activated postural muscles and corresponding VMS, particularly in lumbar part; bone structures of the backbone undergo long pressure (from the backrest), which causes the formation of reversible restrictions in VMS or VMS functional blocks.